Theft is frequently a problem in retail stores as well as in other environments. In other environments, it is desirable to track objects. To address these issues, electronic article surveillance (EAS) systems are installed. Generally, in EAS systems, electronic tags, labels, or similarly titled electronic devices are placed on objects to be protected, or monitored. These EAS tags, or devices, are capable of reflecting a signal back to the broader system. The broader EAS system creates interrogation fields which energized the EAS tags to produce the signals that the tag and the object to which it is attached are in the interrogation fields.
These interrogation fields are frequently set up at exits or entries to an area that is being monitored or protected. Frequently, the antennas that are used to generate the interrogation fields and to monitor for tag signals are housed within pedestals that are placed to each side of an exit. However, these antennas and their controlling electronics can be positioned overhead or within the floor in the area close to the exit.
The controlling electronics for these antennas generate a signal which is transmitted by the antennas and creates the interrogation field. This field energizes or stimulates tags that are passing through the interrogation field, or zone. The tags then produce a signal in response to the interrogation field. This signal from the tags may be created by energy of the field itself, or the tags may have on board power supplies and electronics that reply to the interrogation field. The interrogation field is cycled for periods of transmission and monitoring. The interrogation field initially cycles and broadcast out into the zone being monitored and then the interrogation field is stopped. The antennas of the EAS system then monitor for a tag signal. If a tag signal is detected, it assumed that the tag is improperly in the zone being monitored by the interrogation field, and the EAS system determines that an alarm condition is in effect. The EAS system can then generate an alarm, either an optical alarm such as flashing lights, an audible alarm such as bells, etc., or a system alarm that is broadcast to operator stations.
The signals from the electronic EAS tags are relatively week and it is common to have electro-magnetic noise within the area being monitored by the EAS system. This electro-magnetic noise may the result of other EAS systems in proximity to the system monitoring a given area, or the noise may be a product of other systems such as lighting, motors, etc. When the noise is sufficiently loud, it can mask the presence of an EAS tag during the monitor phase of the EAS cycle, or alternatively, it may produce a false positive when a tag is not actually there. In many cases, a false positive is considered to be worse than missing a tag that is present as it may indicate, falsely, that somebody is attempting to remove an article.
If the noise is the product of another EAS system, then it will have a cyclic profile, similar to the one monitoring a given area. Such a case may occur for retail locations that are located within a mall, for example. In the case of a mall, there are several EAS systems operating in relatively close proximity to each other, each of which will be transmitting interrogation fields and then monitoring for responses.
A given retail outlet will have no control over the EAS system of a neighboring retail outlets electronic article surveillance system. If a neighboring system is cycling at similar rates but at different times, then it will be transmitting an interrogation field while the “home” EAS system is monitoring for tags within its interrogation field or zone. Since the signal of the EAS tags are relatively week, the transmission of a neighboring EAS system may very well appear to be a tag and cause an alarm condition for the home EAS system. Even if the noise source is not another EAS system, it will most typically still have a cyclic profile. Which is to say, the noise source will have periods where it is stronger, and periods where it is weaker.
To combat the effects of noise in an environment, the profile of the noise in an environment can be captured, or recorded, and analyzed. The EAS system experiencing the noise problem can then be tuned to decrease the effect of the noise in the environment. In cases where the noise is the result of neighboring EAS systems, the home EAS system can be tuned to the neighboring EAS system. In this case, the home EAS system is tuned to transmit its interrogation field in synch with the neighboring system so that they are transmitting their interrogation fields at the same times and monitoring for tags at the same times. This gives the home EAS system a quieter time to monitor for tags, since the neighboring system is also at rest and listening for tags. In other cases, rather than tuning the home EAS system to transmit during the peak of environmental electromagnetic noise, such as when a neighboring EAS system is transmitting, the home EAS system is tuned to time its cycle to be in the lull of a noise profile so that it transmits it interrogation field and also monitors for a response at a minimum point in the noise profile in that environment.
Additionally, electronic article surveillance systems use digital signal processors DSPs and other components in their controls. These components are programmable at various levels and upgrades to their programming and firmware are sometimes required. In older, relevant art systems, this upgrade to the programming and firmware is performed by a technician actually going to the site of the EAS system to upgrade the firmware and sometimes to change out components and circuit boards.